Sublimation apparatus



March 13, 1928.

l,662,070 c. A. LXFoRD SUBLIMATION. APPARATUS Filed Aprii 2. 1920 `sup/5,? HM TER.

l J I I I l I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I l I I I I I I I I I I I I I I I I I I I I I l I I I l I I I U81 /MER Patentetlv Mar. 13, 1928.

` UNITED STTES 1,66z,o7o

PATENT OFFICE.

CHA'UNCEY A. LYFORD, OF EAST AUBORA, NEW YORK, ASSIGNOR T NATIONAL NI- LINE & CHEMICAL CO., INC., OF NEW YORK, N. Y., .A CORPORATION OF NEW YORK.

SUBLIMATION APPARATUS.

Application filed April 2,

J This invention relates to an improved sublimation apparatus for the sublimatio'n of chemical materials by the use 'of superheated steam or other heated gas or vapor. In the ordinary forms of sublimers designed for work at high temperatures, difliculty is encountered with many materials because of local overheating of the material where it comes in contact with the walls of the container. Such overheating may result in charring or gumming of the material near the heated walls, while the material away from the walls is heated to a much lower temperature. Owing to such differences in temperature it is sometimes diflicult to determine at just what temperature the process is being operated, and whether parts of the material are sufiiciently heated or other parts overheated. The provision of agitators, for agitating the material during sublimation reduces this difficulty, but the difliculty may nevertheless be encountered to a greater or less extent even when an agltator is provided. Moreover, where the material being sublimed is of a pulverulent or pulverizable character, the agitator may pulverize it so finely that, where a transporting medium is employed, the fine dust of the crude material is carried over with the transporting medium and with the vapors of the material being sublimed, so that the sublimate is contaminated by impurities.

The present inventlon relates to an improved apparatus intended more particularly for the sublimation of material which does not fuse together during sublimation but which is of a porous and permeable character. The invention is well adapted for the. sublimation of materials which have not been finely ground, but which exist -in the form of. lumps, for example, such as come fromthe drying of material taken from a filter press, where the material is of a porous character and where the larger lumps have been broken up.

According to the present invention, the material to be sublimed is placed in a suitable containeror receptacle which is suitably heated and which has a perforatcd bottom upon which the material is supported; and the superheated steam or other gas or vapor is introduced beneath the perforated bottom and caused to pass up therethrough, into and through the material supported 1920. Serial No. 870,802.

removed from the sublimation receptacle and carried to a suitable condenser where the subllmate is separated in a solid state.

The invention includes various features of improvement.

In the accompanying drawings I have illustrated, in a somewhat diagrammatic and conventional manner, two forms of apparatus embodying the invention and the invention will be further described in connection therewith.

In the accompanying drawings: Fig. 1 shows the sublimation apparatus in elevation and with parts in Vertical section; and

Fig. 2 isa Vertical sectional view of a modified form of apparatus.

In the apparatusof Fig. 1 the receptacle or container 1 is provided with a suitable cover 2 having aV charging manhole 3 therein and having an'outlet conduit 4 for the sublimate, this conduit leading to the condenser 14. The receptacle or container 1 has a perforated bottom spaced away from the bottom of the container itself and suitably supported (by means not shown). This perforated bottom is made up of a perforated sheet metal plate 6 having a screen 7 supported thereby and upon which the charge of material to be sublimed is supported. The screen 7 prevents smaller particles from falling through into the Chamber 9 and insures a more uniform distribution of the heating and transporting medium passing upwardly therethrough. The perforated or false bottom divides the vessel or receptacle 1 into a larger upper Chamber 8 and a smaller lower Chamber 9. The chamber 8 has a side opening 10 for the purpose of removi'ng the exhausted material at the end of the operation.

The container 1 is surrounded by a heating ja-cket 11 intended for oil or other suitable medium. The oil jacket is heated and maintained at the desired temperature in any suitable manner, as by direct firing in the furnace 13. Thermometer Wells 5 and 12 are suitably arranged in the .chamber 8 and in the oil jacket. It will be evident that the-oil used in the heating jacket should have a high flash point where the apparatus itself requires a high temperature for its operation. The temperature of the oil or other heat'ing medium in the jackct will vary with the material to be sublimed, but it should be maintained only at about that point which will compensate for the possible heat losses of the su erheated steam or other transporting me ium passing through the apparatus. All the exposed metal parts of the apparatus should be covered with magnesia packing or other insulating covermg (not shown) to prevent condensation o'f the sublimate.

Where superheated steam is supplied as the transporting medium it isv superheated to the proper temperature in the superheater 23 which may be of any suitable construction, and which is shown as an oil-fired su' perheater having oil and air supply pipes 24 and 25. The supcrheated steam, superheated to the proper temperature, is conveyed from the superheater through the pipe 26 and dischar es at 27 into the lower chamber 9 below tle false bottom. From this chamber it passes up through the erforated bottom in a uniform manner and t en passes up through the charge of material to be sublimed, serving to heat the material in a uniform manner and to the proper temperature. The sublimate is carried over with the 'superheate'd steam, through the pipe 4, to

the condenser. The pipe 29 from the superheater to the top of the chamber 8 permits an excess of superheated steam to be introduced to assist in sweeping the vapors from the chamber to the condenser.

The condenserillustrated is provided with a water jacket 15 and with scrapers 16 for keeping the inside cooling surfaces free from any sublimate that condenses thereon, thereby proloting the cooling e'fl'eet of the water jacket. The condenser is also provided with spray nozzles 18 and 19, one for spraying water downwardly at the top and the other for spraying water upwardly from the bottom. lVater is supplied through the pipe 17. Thesublimate and the water condensed in the condenser are passed to a filter for the' separation of the sublimate from the water. As illustrated, this filter is in the form of a perforated plate 20 having a canvas layer 21 thereon.- The sublimate is collected on the filter" while the water is drawn off through the pipe 22 to a suction pump (not shown).

In the operation of the apparatus, the charge to be sublimed, preferably in the form of small lumps, is charged into the compartment 8 through the manhole 3, the manhole cover is secured in place, the oil jacket is heated to a suitable temperature, and the superheated steam is introduced through the pipe 27 from the superheater into the lower Chamber 9 from which it passes upwardly through the false bottom and through the charge supported thereby. The Chamber 9 has a bleeder ol' draw-off pipe 28 for drawing offany water of condensation such as forms during the early part of the operation. When the steam no longer condenses, the discharge opening 28 is closed. The temperature of the sublimation 'and of the oil jacket are readily determined by thermometers placed in the thermometer wells 5 and 12. The temperature is raised to a suitable temperature for the sublimation and is maintained until the sublimation is completed. Steam at a lower temperature is then preferably passed through the apparatus to cool it and the residue is then discharged through the opening 10.

The sublimate together with the superheated steam pass through the pipe 4 to the condenser where condensation is etfectcd either by means of the water jacket 15 or by means of the spray introduced through the spray nozzles 18 and 19, or partly by the water 'acket and partly by the spray, and the su limate is collected on the filter 21 and separated from the condensed steam.

In the apparatus of Fig. 2 the corresponding parts are indicated by the same reference numerals with the sutiix a appended thereto. In the construction illustrated in this figure, however, the oil jacket is omitted and av steam jacket is provided adapted to be heated by the same steam which is used in carrying out'the sublimation operation. The apparatus comprises'the receptacle 1*' having a perforated bottom for containing the charge of material to be sublimed, and this receptacle is surrounded by an outer receptacle 11a which provides an annular steam jacket and a bottom compartment 9' for the superheated steam introduced through the pipe 26. The apparatus is provided with suitable insulating means such us a magnesia covering (not shown).

In the operation of this apparatus, the cover is removed, the receptacle 1, which can be removed from the outer vessel 11', is charged with the material to be sublimed, the cover is replaced, and the operation is then carried on in a manner similar to that above described, by the introduction of the superheated steam through the pipe 26'. This superheated steam has the double function of supplying the heat for the heating jacket and the steam for the sublimation, so that thereceptacle 1'I is surrounded by steam at substantially the same temperature as that which is passing through it for efl'ecting the sublimation. Proper regulation of the steam temperature thus enables the entire sublimation operation to be properly regulated in temperature. The apparatus 'illustrated in Fig. 2 is adapted for smaller l Scale Operations than that of Fig. 1, although the same principles of construction and the same combined use of the steam as the heating means and as the transporting means is equally applicable to larger sized apparatus.

The rate at which the sublimation takes place will depeud in part upon the rate at which the superheated steam is supplied, as well as upon the temperature of the steam, the porosity of the charge, etc. At the outset of, the operation the charge will be progressively raised in temperature by the superheated steam, and. partieularly if the material undergoing sublimation is rapidly sublimed,`the temperature within the receptacle may be materially lower than that of the superhe'ated steam int-reduced. It will usually be some time after theprocess begins before the charge is gradually heated to its maximum temperature, and it is usually 'desirable to secure this gradual and progressive increase in tempcratm'e so that. the subliming operation will be continuous and progressive. Near the end of the sublimation the temperature can with advantage be somewhat incrcased to complete the sublimation of materials which have not been previously sublimed.

The physical Character of the sublimate will vary great-ly with the method of condensatiou. The use of a finely divided water spray in the condensertends to produce a fiuelydivided sublimate, and the condcnsed steam and added water spray serve to. dis- 'solve soluble constitueuts and thereby purify the sublimate. It is therefore of advantage to efi'ect the condensation of the sublimate by means of a water spray so that the sublimate will be obtained in a puritied state and in a finely divided condition well adapted for subsequent treatment. r

From the above description it will be seen that mechanical agitation of the charge undergoing sublimation is avoided, and that local overheating or uneven heating of the charge is avoided or reduced to a minimum, while the entire charge is subjected to the uniform heat-ing action of the superheated steam which serves as both the heating and the t-ransporting medium. As a result, the production of fine dust, such as may result from mechanical agitation, is avoided, and the carrying over of fine dust with the steam is correspondingly reduced. The only agitation to `which the charge is subjected is that incident to the passage of the steam upwardly therethrough, but this will ordinarily be so slight that it will be entirely unobjectionable, and may even be desirable in promoting the uniformity of distribution of the steam through the material.

The apparatus of the present invention is applicable to the sublimation of organic or material, and particularly where the material does not fuse together, but maintains a solid state throughout the operation. Materials can thus be'sublimed which would be 'easily disintegrated into an impalpable powder if subjected to agitation, without any apprecia'ble production of such a powder or carrying over of fine material with the transporting medium. plicable to the sublimation of material for the purpose of changing its physical state and where purification from a non-sublimable residue is not effected. The invention is of particular value, however, for the separat-ion of sublimable'material from a residu'e of a bulky or light-weight Character.

The improved appara-tus .of the present invention is of special value for the sublimation of benzanthrone and the production of a puriticd banzanthrone from crude benzanthrone; but I do notclaim herein the method of sublimation of bcnzanthrone, etc., inasmueli as this forms the subject-matter of a. separate process, application Serial No. 370,801, filed of even date herewith.

I claim:

1. A sub'limation apparatus eomprising a 'containcr for the material to be sublimed, means for introducing steam int-o the container beneath said material, means for int'roducing steam into said container above said material and means for condensing the sublimed material.

2. A sublimation apparatus adapted for the sublimation of organic chemical materialswithout' locall overheating of the material, comprising a perforated support for supporting the material to be sublimed, means for supply'ing and introducing superheated steam beneath said supporting means, means for supplying and introducing superheated steam above said and means for condensing terial.V

3. A' sublimation apparatus comprising a container for the material to be sublimed, means for passing superheated steam through said material, means for simultaneously passing steam over the surface of said material, and means for condensing the sublimed material.

In testimony whereof I aflix my signature.

CHMJNCEY'v A. LY'FORD.

the sublimed ma- The invention is also ap-` morganic material from a non-sublimable supporting means, 

